WO2001001408A1

WO2001001408A1 - Optical recording medium and method for reading optical recording medium

Info

Publication number: WO2001001408A1
Application number: PCT/JP2000/004256
Authority: WO
Inventors: Yoichiro Sako; Hiroshi Ogawa; Tatsuya Inokuchi
Original assignee: Sony Corporation
Priority date: 1999-06-28
Filing date: 2000-06-28
Publication date: 2001-01-04
Also published as: CN1321307A; AU5570100A; KR20010072350A; EP1111604A1

Abstract

An optical disk having a multilayer of recording layers comprises a substrate having a light transmittance, a first recording layer provided on one side of the substrate, a second recording layer provided on the first recording layer and having a read-in area on which at least data necessary to read data is recorded, and an intermediate layer provided between the first and second recording layers. The first recording layer is so provided to extend from outside the read-in area.

Description

^Item: reading method Technical Field of the Invention The optical recording medium and the optical recording medium is directed to the optical recording medium and a method of reading an optical recording medium for reading data recorded on the optical recording medium having a plurality of recording layers. BACKGROUND ART Conventionally, as a recording medium for various types of information such as audio information and video information, an optical disk that reproduces information recorded on the recording medium using a light beam has been widely used. With respect to this type of optical disk, there has been proposed an optical disk having a multi-layered recording layer in order to increase the amount of recordable information.

As an optical disk having a multi-layered recording layer, an optical disk that irradiates a light beam from one side of a substrate to reproduce data recorded on each recording layer has been proposed.

In this optical disc, a first recording layer is provided on one surface of a substrate having optical transparency, and a second recording layer is provided on the first recording layer via an intermediate layer having optical transparency. I have. The first recording layer is a translucent film that transmits a certain amount of light beam and reflects a certain amount of light beam so that the light beam incident from the substrate side is incident on the second recording layer side. Formed Have been. The first recording layer located on the light beam incident side is made of a translucent film, and the second recording layer is made of a high-reflectance layer. Light can be obtained, and information signals recorded in each recording layer can be read.

Reproduction of a data signal recorded on each recording layer of an optical disc having a plurality of recording layers is performed by controlling a focus position of a light beam applied to the optical disc. That is, the data recorded on the desired recording layer can be reproduced by focusing the light beam on the desired recording layer.

By the way, the conventionally proposed optical disc having a plurality of recording layers is provided such that each recording layer is superimposed on a common area extending over the inner and outer circumferences of the optical disc. As described above, when a plurality of recording layers are provided so as to be completely superimposed, the reflectance of another recording layer superimposed on one recording layer is only the reflectance limited to the transmittance of one recording layer. It is no longer possible to obtain sufficient reflectivity. As a result, the signal level based on the light reflected from the other recording layer is reduced, and the signal cannot be reproduced by a conventionally used optical disc reproducing apparatus that requires a high reflectivity of the recording layer. Therefore, if an attempt is made to increase the light transmittance of one recording layer so that the reflectivity of the other recording layer increases, the reflectance of one recording layer decreases, and the other recording layer and the other recording layer decrease. It is difficult to configure an optical disk reproducing apparatus that can reproduce both of the recording layers.

In addition, each recording layer of an optical disk provided with a plurality of recording layers that has been conventionally proposed has a similar structure over the inner and outer peripheries. Each recording layer is necessary for reading data such as audio information and video information on the inner side A lead-in area for recording control data is provided, and a data area for recording data such as audio information and video information is provided on the outer peripheral side of the lead-in area. Here, the control data required for reading data includes address information indicating a recording position of the data recorded in the data area.

As described above, each recording layer is formed on the substrate of the optical disk so as to be superimposed almost over the entire area, and when control data and the like are recorded in the same structure, the recording layer is mounted on the optical disk reproducing apparatus and the recording layer is attached to each recording layer. When reproducing data such as recorded audio information or video information, the control data recorded in the lead-in area of one recording layer that is read first is irradiated to, for example, one recording layer. The component of the light beam transmitted through one recording layer is reflected by the other recording layer, so that the control data recorded in the lead-in area of the other recording layer becomes a noise component. The data for controlling the read-in area may not be accurately read, so that a desired recording layer may not be selected, or the reproducing operation of the recording layer may not be performed. DISCLOSURE OF THE INVENTION Accordingly, an object of the present invention is to select each recording layer reliably while increasing the number of recording layers in order to increase the recording capacity, and to accurately reproduce data recorded in each recording layer. It is an object of the present invention to provide an optical recording medium capable of reading and a method of reading the same.

Another object of the present invention is to use the conventional optical disk with compatibility with an optical disk used for an optical disk player which requires a high reflectance. It is an object of the present invention to provide an optical recording medium which can be read and a reading method therefor.

An optical recording medium according to the present invention proposed to achieve the object as described above includes a substrate having optical transparency, a first recording layer provided on one surface of the substrate, A second recording layer provided so as to be stacked with the first recording layer and having at least a lead-in area in which data required for reading data is recorded; a first recording layer; And an intermediate layer provided between the recording layer and the second recording layer. The first recording layer is provided from outside the lead-in area.

Further, the optical recording medium according to the present invention is provided with a substrate having optical transparency, a first recording layer provided on one surface of the substrate, and a layer laminated with the first recording layer. A second recording layer having at least a lead-in area in which data required for reading data is recorded, and an intermediate layer provided between the first recording layer and the second recording layer And. In this optical recording medium, at least a part of a portion of the first recording layer facing the lead-in layer is a mirror surface portion.

Furthermore, the optical recording medium according to the present invention has a substrate having optical transparency, and at least a first recording layer and a second recording layer, and the first recording layer and the second recording layer. Is provided on one surface of the substrate, and the other recording layer is provided so as to be laminated with the above-mentioned one recording layer and an intermediate layer, and at least data required for reading data over time is provided. There is provided a lead-in area in which is recorded.

A method for reading an optical recording medium according to the present invention includes a substrate having optical transparency, at least a first recording layer and a second recording layer, and the first recording layer and the second recording layer. Providing one of the layers on one side of the substrate, The other recording layer is provided so as to be laminated with the one recording layer and the intermediate layer interposed therebetween, and at least a lead-in area in which data necessary for reading data is recorded is provided. The data in the lead-in area of the second recording layer of the recording medium is read, and the data of the first recording layer is read after reading the data of the lead layer.

The method for reading an optical recording medium according to the present invention includes the steps of: laminating a substrate having optical transparency, a first recording layer provided on one surface of the substrate, and the first recording layer. A second recording layer having a read-in area in which at least data required for reading data is recorded, and a second recording layer between the first recording layer and the second recording layer. After reading the data in the read-in area of the read-in area of the second recording layer of the optical recording medium in which the first recording layer is provided from the outside of the read-in area, and reading the data in the read-in area. Read the data of the first recording layer.

In addition, the method for reading an optical recording medium according to the present invention includes the steps of: laminating a substrate having optical transparency; a first recording layer provided on one surface of the substrate; A second recording layer having a lead-in area provided with at least data required for reading data, and a first recording layer and a second recording layer. An intermediate layer provided between the first recording layer and a portion of the second recording layer of the optical recording medium having at least a portion facing the lead-in area of the first recording layer, and After reading the evening, the data in the first recording layer is read after reading the data in the lead area.

Still further, an optical recording medium according to the present invention comprises: a substrate; A first recording layer provided on the other side, a second recording layer provided so as to be laminated on the first recording layer, and a first recording layer and the second recording layer. And an intermediate layer provided therebetween. The optical recording medium is provided such that the first recording layer and the second recording layer are mutually deviated in the layer direction.

Further, in the reading method of the optical recording medium according to the present invention, the data is recorded in the lead-in area from the optical recording medium having the first recording layer having the lead-in area provided in a state of being laminated on the substrate. Data is read, and it is determined whether or not a second recording layer exists between the recording layer and the substrate based on the data read from the lead-in area, and the second recording layer exists. When it is determined, the second recording layer is read based on the control data recorded in the leader-in area.

Further objects of the present invention and specific advantages obtained by the present invention will become more apparent from the description of the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an optical disc according to the present invention.

FIG. 2 is a plan view showing an optical disc according to the present invention.

FIG. 3 is a diagram showing a state in which the first and second recording layers provided on the optical disk according to the present invention are irradiated with a light beam.

FIG. 4 is a sectional view showing another example of the optical disk according to the present invention. FIG. 5 is a block circuit diagram showing an optical disk reproducing apparatus using the optical disk according to the present invention.

FIG. 6 shows that the optical disk according to the present invention is irradiated with a light beam to generate a force. FIG. 3 is a circuit diagram for detecting a stray signal.

FIGS. 7A to 7C are plan views showing a state in which a light beam is applied to a four-division detector for detecting a focus error signal using the astigmatism method.

FIGS. 8A and 8B are diagrams showing an RF sum signal and a focus error signal obtained when a light beam is applied to an optical disc having the first and second recording layers formed opposite to each other.

9A and 9B are diagrams showing an RF signal and a focus error signal obtained when the optical disk according to the present invention is irradiated with a light beam. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an optical recording medium and a method for reading the optical recording medium according to the present invention will be specifically described.

First, as shown in FIG. 1, an optical disc 1 as an optical recording medium according to the present invention includes a substrate 2 made of a synthetic resin such as a polycarbonate resin having optical transparency, glass, or the like. On one surface side of the substrate 2, for example, a pit pattern 3 which is a minute uneven pattern corresponding to audio information to be recorded is provided. The pit pattern 3 is configured so that a plurality of pits based on the information to be recorded form a spiral or concentric recording track. When the substrate 2 is made of a synthetic resin, the pit pattern 3 is formed at the time of molding the substrate 2 by being transferred from a stamper when the substrate 2 is formed by injection molding. The pit pattern 3 is formed using the 2P (Photo Polymerization) method when the substrate 2 is formed of glass. It is. The 2P method fills a glass substrate and a disk stamper with a photocurable resin such as an ultraviolet-curable resin and cures the photocurable resin by irradiating light from the glass substrate side. In this method, the pattern is transferred to a photocurable resin.

The substrate 2 used for the optical disk 1 according to the present invention is formed by injection molding a polycarbonate resin, and recording information is recorded as a pit pattern 3 on one surface side of the substrate 2. This substrate 2 has a diameter of 12 cm and a thickness of approximately 1.2 mm, similarly to a conventional so-called compact disk substrate, which is an optical disk having a diameter of 12 cm.

On one surface of the substrate 2 on which the pit pattern 3 is formed, a first recording layer 4 is provided so as to cover the pit pattern 3 as shown in FIG. The first recording layer 4 is a semi-transmissive film that transmits a certain amount of the light beam irradiated from the substrate 2 side and reflects a certain amount. For example, the first recording layer 4, using the _{_{S i 3 N 4, S i}} 0 2 such as a silicon-based material, is deposited to 1 0 0 nm~ 5 0 0 of about nm thick. In this case, the first recording layer 4 is formed as a multilayer of S i ₃ NJ S i 02 films. The Si ₃ N ₄ film and the SiO ₂ film constituting the first recording layer 4 are formed on the substrate 2 by a vacuum evaporation method or a sputtering method.

On the first recording layer 4, a second recording layer 6 is formed via an intermediate layer 5 made of a light-transmitting ultraviolet-curable resin or the like. The intermediate layer 5 optically separates the first recording layer 4 and the second recording layer 6 so that the first recording layer 4 and the second recording layer 6 are not located within the depth of focus of an objective lens that focuses a light beam on these recording layers 4 and 6. It plays a role. For example, the intermediate layer 5 is formed to have a thickness of about 30 m. When the thickness of the intermediate layer 5 is small, The first and second recording layers 4 and 6 are located within the depth of focus of the objective lens, and sufficiently separate the reflected light from the first recording layer 4 and the reflected light from the second recording layer 6 This makes it difficult to accurately detect each reflected light, and if the intermediate layer 5 is too thick, the light beam applied to the recording layer 6 will cause spherical aberration and the like. The appropriate thickness of the intermediate layer 5 is selected in consideration of the points.

The intermediate layer 5 is formed by applying a photo-curable resin such as an ultraviolet-curable resin onto the first recording layer 4 by a spin coating method, irradiating ultraviolet rays or the like, and curing the applied resin. . Alternatively, the intermediate layer 5 may be formed by laminating an ultraviolet curable resin or the like in a plurality of times with a thickness of about 5 μm to 10 zm. Further, the intermediate layer 5 may be formed by attaching a transparent sheet to the first recording layer 4.

On one surface side of the intermediate layer 5, a pit pattern 7, which is a minute uneven pattern corresponding to, for example, audio information recorded on the second recording layer 6, is formed. The pit pattern 7 is configured such that a plurality of pits based on information recorded similarly to the above-described pit pattern 3 form spiral or concentric recording tracks. The bit pattern 7 is formed on one surface of the _c intermediate layer 5 which can be formed using the above-described 2P method used when forming the pit pattern on the above-mentioned glass substrate. The second recording layer 6 is formed so as to cover the pattern 7 and to be stacked on the first recording layer 4. The second recording layer 6 reflects the light beam transmitted through the first recording layer 4 and radiated to the optical pickup located on the substrate 2 side, so that the aluminum (A 1), gold (A u), High reflectivity of silver (Ag) etc. It is formed by forming a film made of a material such as a metallic material on one surface of the intermediate layer 5. On the second recording layer 6, a protective layer 8 made of an ultraviolet curing resin or the like is provided so as to cover the second recording layer 6 in order to protect the surface of the second recording layer 6. The protective layer 8 is formed by applying an ultraviolet curable resin or the like onto the second recording layer 6 by spin coating and then irradiating the applied resin with ultraviolet light or the like to cure the applied resin.

As shown in FIG. 2, the optical disc 1 has a center hole 11 at the center and a clamping area 12 around the center hole 11. In this optical disk 1, the center hole 11 is engaged with a centering portion provided at the center of the disk table of the disk rotation drive mechanism of the optical disk reproducing apparatus, and the clamping area 12 is placed on the disk table. In addition, the optical disk 1 is centered on the disk table by being clamped by the clamp member, and is mounted so as to be rotatable integrally with the disk table.

As described above, the optical disc 1 is provided with the clamping area 12 which is clamped by the disc rotation drive mechanism on the inner peripheral side, and the first and second recording layers 4 and 6 on the outer peripheral side of the clamping area 12. Provided.

By the way, as shown in FIG. 1, the second recording layer 6 provided so as to be laminated on the first recording layer 4 is located further inward of the portion where the first recording layer 4 is provided. It extends to the area near the clamping area 12. When the optical disc 1 is mounted on an optical disc playback device, the first and second recording layers 4 and 6 have an inner peripheral area that does not face the first recording layer 4 of the second recording layer 6. Data recording There is provided a lead-in area 15 in which at least a part of control data to be read out prior to playback of audio information or the like recorded in advance in areas 13 and 14 is recorded. The control data recorded in the read area 15 is, for example, the second light beam of the light beam which constitutes a part of the control data necessary for reading out the data recorded in the second recording layer 6. Data indicating the focus offset amount for controlling the focusing position with respect to the recording layer 6, data for controlling the tracking of the light beam, and control necessary for reading the data recorded on the first recording layer 4. For example, it is data indicating a focus offset amount for controlling a focusing position of the light beam with respect to the first recording layer 4 and a data for tracking the light beam, which are a part of the data for use. The focus offset amount referred to here is an objective lens for moving the focal position of the light beam focused by the objective lens to one of the first recording layer 4 and the second recording layer 6. Refers to the DC signal component for moving in the direction of the optical axis of the objective lens.

The lead-in area 15 includes data recorded in the data recording area 14 of the second recording layer 6 as control data for controlling reading of data recorded in the second recording layer 6. Information such as inventory information indicating the contents of the evening, head address information indicating the recording start position of each data, or absolute time information is also recorded.

The control data recorded in the re-recording area 15 is also the same as the data recorded in the data recording areas 13 and 14. Recorded by Evening Seven.

Also, in the optical disc 1 according to the present invention, since the lead-in area 15 is provided only on the second recording layer 6, this optical disc 1 When the disc is mounted on a disc playback device, the control data recorded in the read-in area 15 provided in the second recording layer 6 is read out and then read out to the first recording layer 4 or the second recording layer 6. Playback of recorded data is performed. Therefore, in the lead-in area 15, in addition to the address information or the absolute time information indicating the start position of the data recording area 14 of the second recording layer 6, the innermost peripheral position of the first recording layer 4 and the data recording At least information necessary for accessing the first recording layer 4, such as address information such as the start position of the area 13 or absolute time information, is recorded.

The lead-in area 15 is provided in an area that can be scanned by a light beam emitted from an optical pickup provided on the optical disk reproducing device when the optical disk reproducing device is mounted. That is, the read-in area 15 is provided so as to start from a position on the outer peripheral side of the innermost peripheral position where data can be read from the optical disk 1 when the optical pickup is moved in the inner peripheral direction of the optical disk 1. I have.

As described above, the optical disc 1 according to the present invention is formed such that the start end side of the second recording layer 6 is extended to the inner peripheral side of the first recording layer 4, and the second recording layer 6 is extended. Since a lead-in area 15 is provided in the portion, the first recording layer 4 has a lead-in area as shown in FIG.

It will be provided in the area outside of 15. The portion of the optical disc 1 where the lead-in area 15 of the second recording layer 6 is provided reflects a light beam from the substrate 2 on which the light beam is incident to the second recording layer 6 The structure is such that no layer is provided. For this reason, the optical beam enters without being attenuated by the first recording layer 4 and is reflected by the lead-in area 15, so that the noise by the first recording layer 4 as described in the related art. Lead-in area without adding The control data recorded in 15 can be read with high accuracy. When reading the control data recorded in the lead-in area 15 provided in the second recording layer 6, the light beam reflected by the first recording layer 4 can be eliminated, and the second The component reflected by the first recording layer 4 is added to the light beam reflected by the lead-in area 15 of the recording layer 6, so that the light beam can be read accurately without including a noise component.

Meanwhile, the optical disc 1 according to the present invention has a photodetector in which a light beam is irradiated from the substrate 2 side, and the return light beams reflected from the first and second recording layers 4 and 6 are arranged on the substrate 2 side. The data recorded on the first and second recording layers 4 and 6 are reproduced by detecting the data. The first recording layer 4 is formed as a semi-transmissive film that allows a predetermined amount of light beam to pass through to the second recording layer 6 side, and the second recording layer 6 is formed on the first recording layer 4. It is formed to reflect the transmitted and irradiated light beam with high efficiency. That is, the reflectance of the second recording layer 6 is higher than the reflectance of the first recording layer 4.

More specifically, the reflectance of the first recording layer 4 of the optical disc 1 according to the present invention is 11%, and the reflectance of the second recording layer 6 is 99%. Here, assuming that the diffusion and absorptivity of the light beam of the substrate 2 formed of polycarbonate resin is 5%, as shown in FIG. 3, when the light beam is incident from the substrate 2 side, the first is reflected as the recording layer 4 1 0 percent return of the light beam L _2, 8 5% of incident on the second recording layer 6 is transmitted through the first recording layer 4. At this time, since the diffusion and absorptivity of the light beam of the intermediate layer 5 is almost zero, the light is almost incident on the second recording layer 6. The light beam L ₃ incident on the second recording layer 6 has 99% Is reflected on the second recording layer 6 having a reflectivity, return of the light beam L ₄ with Do connexion reflectance is 1 1% first recording layer 4 and the diffusion and absorption of the transmission 5% board 2 And output to the outside of the optical disc 1. Return of the light beam L ₄ of the return reflected from the second recording layer 6, the light beam L that is first incident on the substrate 2 is about 71 percent.

Further, as another example of the optical disc 1 according to the present invention, assuming that the reflectance of the first recording layer 4 is 20% and the reflectance of the second recording layer 6 is 99%, the first recording first it is reflected as a light beam L ₂ of the light beam L incident on the substrate 2, 1 8% return from layer 4, the light beam L that is first incident on the substrate 2 from the second recording layer 6! About 5 7% is reflected as a light beam L ₄ of return.

As described above, by reducing the reflectance of the first recording layer 4 and increasing the light transmittance so that the second recording layer 6 has a large reflectance, the reflected light reflected from the second recording layer 6 can be reduced. The light amount of the light beam can be sufficiently secured. The data recorded in the data recording area 14 of the second recording layer 6 having a high reflectivity can be sufficiently reproduced even in a conventional so-called compact disc optical disc reproducing apparatus requiring a high reflectivity. be able to.

Even in the case where the reflectance of the second recording layer 6 is transmitted and the light beam is irradiated through the first recording layer 4, the conventional optical disc reproducing apparatus that requires a high reflectance is sufficient. By increasing the reflectance until the data can be read, the control data recorded in the lead-in area 15 provided in the second recording layer 6 can be read with higher accuracy o

In addition, the lead-in area 15 includes first and second recording layers 4 and 6. As control data that is read prior to reproduction of data such as audio information recorded in advance in the recording areas 13 and 14 of the

Data on the reflectance of the first recording layer 4 is recorded. At least data on the reflectance of the first recording layer 4 is recorded in the lead-in area 15. The data relating to the reflectance of the first recording layer 4 is read out, and the gain of the amplifier circuit for amplifying the read data and the loop gain of the servo circuit described later are switched in advance, for example. Can be read accurately. Of course, the data on the reflectance of the second recording layer 6 is recorded in the lead-in area 15 and the data on the reflectance of the second recording layer 6 is read out. The data recorded on the second recording layer 6 can be read by switching the gain of the amplifier circuit or the loop gain of the servo circuit based on the data on the reflectance of the second recording layer 6 .

Further, the type data indicating that the first recording layer 4 is provided in addition to the second recording layer 6 in the lead-in area 15 was recorded, so that the optical disc 1 was mounted on the optical disc reproducing apparatus. Sometimes, by reading the data indicating that the first recording layer 4 is provided, it is possible to immediately identify the optical disc 1 as a multilayer optical disc. Based on the read type data, if it is immediately recognized that the optical disc 1 mounted on the optical disc reproducing apparatus is an optical disc provided with the first recording layer 4, each of the recording layers 4, 6 The playback mode can be switched to the playback mode in which the playback of the data recorded in the unit is performed.

The optical disk 1 described above is a light beam incident on the optical disk 1. Although the reflectivity of the second recording layer 6 is higher than the reflectivity of the first recording layer 4 in the reflectivity represented by the percentage of the amount of return light of the system, the return light from the first recording layer 4 is The light may be larger than the return light from the second recording layer 6. For example, assuming that the reflectance of the first recording layer 4 is 60% and the reflectance of the second recording layer 6 is 99%, about 54% from the first recording layer becomes return light, Approximately 15% of the light from the recording layer 6 is returned light. When the first and second recording layers 4 and 6 are formed at such a ratio of the return light, the lead-in area is provided on the first recording layer 4 and the first recording layer 4 is provided, contrary to the above-described example. Since the second recording layer 6 is not provided on one surface of the intermediate layer 5 facing the lead-in area provided on the recording layer 4 of the second recording layer 4, the second recording layer has a large reflectance and a low light transmittance. The control data recorded in the lead-in area provided in the first recording layer 4 can be read with high reflectivity without being affected by the control signal 6.

In the optical disc 1 described above, as shown in FIG. 1, the first recording layer 4 is provided in an area corresponding to the lead-in area 15 provided in the second recording layer 6 on the first recording layer 4 itself. Although the first recording layer 4 is provided only in the area outside the lead-in area 15, the present invention is not limited to this example, and the pit pattern corresponding to the control data is not provided on the substrate 2. As shown in FIG. 4, a flat surface may be used, and a mirror surface portion 21 in which only the first recording layer 4 is formed on the flat surface may be used.

As shown in FIG. 4, data such as control data is not recorded in the area of the first recording layer 4 corresponding to the lead-in area 15 provided in the second recording layer 6, ie, By reading the data recorded in the lead-in area 15 by leaving no In this case, the signal component reflected by the first recording layer 4 of the light beam applied to the optical disc 1 is prevented from being added as a noise component to the read signal of the second recording layer 6 and accurate. The data in the lead-in area 15 can be read.

In the optical disc 1 according to the present invention, as described above, the lead-in area 15 in which at least data necessary for reading data is provided in the second recording layer 6 is provided. Data reading is started from the side of the second recording layer 6 provided with the area 15. By reading the data in the lead-in area 15 first, the start of reading data such as audio information recorded on the first and second recording layers 4 and 6 can be easily controlled. The selection of the first and second recording layers 4 and 6 can be easily performed based on the control data recorded in the lead-in area 15. At this time, the reflectance of the first recording layer 4 and the first recording layer 4 are stored in the lead-in area 15 as data required for reading data recorded on the first recording layer 4. By recording the type of data indicating that the data is provided, it is possible to set the gain of the amplifier circuit and servo circuit on the optical disk reproducing apparatus side by reading the read data in the read-in area 15. Switching can be set immediately according to the type of optical disc, and even if the optical disc has the first recording layer 4, the data recorded on the first recording layer 4 can be easily reproduced.

A method for reading data such as audio information recorded on the optical disc 1 configured as described above will be described.

As shown in FIG. 5, an optical disc reproducing apparatus for reproducing the optical disc 1 according to the present invention comprises a spin optical disk drive for rotating the optical disc 1. A disk rotation drive mechanism having a disk table provided at the tip of a rotating shaft of the spindle motor 31 and rotating the optical disk 1 mounted on the disk table by the spindle motor 31; The optical pickup 32 scans the first or second recording layer 4, 6 of the optical disc 1 with a light beam and reads the data recorded on the first or second recording layer 4, 6. It has. The optical pickup 32 is moved in the radial direction of the optical disc 1 by the feed mechanism 33.

The optical pickup 32 includes a semiconductor laser 34 as a light source for emitting a light beam irradiated on the optical disc 1, and a light beam L emitted from the semiconductor laser 34 for the first or second optical disc 1. Optical elements such as an objective lens 35 for irradiating the recording layers 4 and 6 while being selectively focused, and a photodetector 3 for detecting a returning light beam reflected from the first or second recording layers 4 and 6 6 and so on. The objective lens 35 is driven by the actuator 37 in two directions orthogonal to each other in a focusing direction parallel to the optical axis of the objective lens 35 and a tracking direction in a plane direction orthogonal to the optical axis of the objective lens 35. And is driven and displaced in the focusing direction and / or the tracking direction based on a focus error signal and / or a tracking error signal obtained by detecting a return light beam.

The objective lens 35 includes a focus off cell for controlling a focusing position of an optical beam included in the control data recorded in the lead-in area 15 provided on the second recording layer 6 of the optical disc 1. The focus position on the first or second recording layer 4 or 6 is selectively controlled based on the data indicating the scanning amount. The optical disk reproducing apparatus for reproducing the optical disk 1 according to the present invention comprises: an optical disk 1 placed on the disk table of the disk rotation driving mechanism described above; The optical disc 1 is moved to a position corresponding to the position where the lead-in area 15 is provided by the feed mechanism 33 based on a control signal from the optical disc 1. In this example, the lead-in area 15 is provided on the inner peripheral side of the second recording layer 6 of the optical disc 1 as shown in FIG. The lead-in area 15 is scanned by the light beam which is moved to the inner peripheral side of the disk 1 and condensed by the objective lens 35. When the lead-in area 15 is scanned, the return light beam reflected by the lead-in area 15 is detected by the photodetector 36 via the objective lens 35. As shown in FIG. 6, the photodetector 36 includes a light receiving section 41 divided into first, second, third, and fourth photodetecting sections 41a to 41d. The return light beam reflected from the lead-in area 15 is incident on the light receiving part 41 of the light detector 36, and the first to fourth light detecting parts 41 a to 41 d of the light receiving part 41 are provided. Therefore, based on the detected outputs from the photodetectors 41 a to 41 d, an RF signal RF, which is a read signal of data recorded in the lead-in area 15 by an RF amplifier 48 described later, and a focus error One signal FE is detected.

The RF sum signal RF is obtained as a sum signal obtained by adding detection signals detected by the first to fourth light detection units 41 a to 4 Id by the RF amplifier 48. That is, the detection output (A + C) output from the first addition circuit 42 that adds the detection signals 8 and C of the first and third light detection sections 41 a and 410 of the light receiving section 41. ) And the second and fourth photodetectors 4 1 b, 4 Addition of the detection output (B + D) output from the second addition circuit 43 that adds the detection signals B and D of 1d by the third addition circuit 44 causes the RF signal RF (two A + B + C + D), and the RF signal RF is also the intensity signal of the light beam reflected from the lead-in area 15. The first adder 42, the second adder 43, and the third adder 44 constitute an RF amplifier 48 described later.

The focus error signal FE is detected by the astigmatism method, and the focal point of the light beam emitted from the objective lens 35 to the lead-in area 15 is the objective lens 35 of the lead-in area 15 Side, and when defocused, the shape of the beam spot S of the returning light beam reflected from the lead-in area 15 is, as shown in FIG. The ellipse has a major axis in the direction extending across the photodetectors 4 la and 4 1 c, and when the focal point of the light beam is on the lead-in area 15, that is, in the focused state, the shape of the beam spot S is As shown in FIG. 7B, the first to fourth photodetectors 41 a to 41 d form a circular shape, and the objective lens 35 is positioned close to the lead-in area 15. Focus is on the protective layer 8 side behind the lead-in area 15 When location, the shape of Bimusupo' DOO S, as shown in FIG. 7 C, an ellipse and the direction across the second and fourth optical detection section 4 1 b, 4 1 d and the major axis. In this way, the shape of the beam spot S changes according to the focusing position of the light beam, and the difference in the amount of light irradiated to the first to fourth light detection units 41a to 41d is detected to detect the focus error. One signal FE is detected. That is, the focus error signal FE is generated by the first and third light detecting sections 41 a of the light receiving section 41, 41 The detection output (A + C) output from the first addition circuit 42 that adds the detection signals A and C of 1c, and the detection of the second and fourth photodetectors 41b and 41d It is generated by subtracting the detection output (B + D) output from the second addition circuit 43 for adding the signals B and D by the subtraction circuit 45. The focus error signal FE [= {(A + C)-(B + D)}] is supplied to the servo circuit 50. The servo circuit 50 controls the actuator 37 based on the supplied focus error signal FE, and drives the objective lens 35 in the focus direction so that the light beam is focused on the lead-in area 15. Displace. The subtraction circuit 45, together with the first, second, and third addition circuits 42, 43, and 44, constitutes an RF amplifier 48 described later.

By the way, the optical disk reproducing apparatus for reproducing the optical disk 1 according to the present invention, when starting scanning of the lead-in area 15 with a light beam from the optical pickup 32, the objective lens 35 is moved from the lead-in area 15 It is controlled so that the focal point of the light beam irradiated to the lead-in area 15 by being driven and displaced in the direction approaching from the separated position is located.

Here, for example, when an optical disc provided with the first recording layer 4 is mounted up to a position facing the lead-in area 15 provided in the second recording layer 6 as shown in FIG. 8A and 8B, the light beam reflected from the first recording layer 4 is detected by the photodetector 36, and the RF based on the light beam reflected from the first recording layer 4 A sum signal rf and a focus error signal fe are generated, and thereafter, a light beam transmitted through the first recording layer 4 and reflected by the lead-in area 15 of the second recording layer 6 is converted to a photodetector 36. , And lead-in area 1 5 The RF sum signal RF and the focus error signal FE based on the light beam reflected from the detector are detected.

When the optical disc 1 shown in FIG. 1 is mounted on the optical disc reproducing apparatus, the first recording layer 4 for reflecting the light beam is not provided at a position facing the lead-in area 15. 9A and 9B, only the light beam reflected from the lead-in area 15 of the second recording layer 6 is detected by the photodetector 36 and reflected from the lead-in area 15 The RF sum signal RF and the focus error signal FE based on the light beam obtained are obtained. Therefore, only the RF sum signal RF and the focus error signal FE based on the light beam reflected from the lead-in area 15 of the second recording layer 6 of the optical disc 1 shown in FIG. 1 can be detected. The light beam from the optical pickup 32 is surely focused on the second recording layer 6 provided with the lead-in area 15, and the data recorded on the lead-in area 15 is recorded on the first recording layer 4. It can be read with high accuracy without including a noise component generated by transmitting light.

As shown in FIGS. 8A and 8B, even in the optical disc 1 in which the portion facing the lead-in area 15 of the first recording layer 4 as shown in FIG. Since the amount of the light beam reflected from the portion 21 is extremely small, the mirror surface portion 21 generates an RF sum signal RF and a focus error signal FE based on the light beam reflected from the lead-in area 15. Generated RF signal rf and focus error —Signal: Since the signal level of fθ is small, the RF signal RF and focus error signal FE based on the light beam reflected by the lead-in area 15 are reliably detected. So, in the lead-in area 15 The light beam from the optical pickup 32 can be surely focused, and the data recorded in the lead-in area 15 can be read with high accuracy.

As described above, the optical beam is first irradiated onto the lead-in area 15 of the optical disc 1, and the audio information recorded on at least the first and second recording layers 4 and 6 recorded on the lead-in area 15 The control disk required for reading data such as data is read out, and the optical disk is reproduced based on the control data read out from the lead-in area 15. It is determined whether or not the first recording layer 4 is present on the optical disc 1 loaded in the apparatus, and the first and second recording layers 4 and 6 are used to determine whether the first and second recording layers 4 and 6 have reflectivity. After the amplifier circuit for reproducing the data recorded on the recording layers 4 and 6 of the amplifier, for example, the gain of the RF amplifier 48 or the loop gain of the servo circuit 50 described later is selected and switched, the system Based on the control signal from the controller 52, the objective lens 35 is The spot of the light beam that is moved in the optical axis direction of the object lens 35 and condensed by the objective lens 35 is moved to one of the first recording layer 4 and the second recording layer 6. You. In this state, each servo loop of the focus servo and the tracking servo by the servo circuit 50 is already closed, and the optical disc 1 is also rotationally driven by the spindle motor 31 at a constant linear velocity.

As described above, in the optical disc 1 according to the present invention, since the data recorded in the lead area 15 is first read, the data recorded in the first recording layer 4 is stored in the lead-in area 15. Reading is started after reading the recorded data. By recording the minimum data necessary for reading data recorded on the first and second recording layers 4 and 6 in the lead-in area 15, Can select the second recording layers 4 and 6 and read data recorded in these recording layers 4 and 6.

Further, in the optical disc 1 according to the present invention, since the data recorded in the lead-in area 15 provided in the second recording layer 6 is first read out, the light incident on the second recording layer 6 is read. By setting the reflectivity of the beam to a reflectivity that enables reproduction by a conventionally used optical disc reproducing device that requires a high reflectivity, the lead-in area is reduced by the conventionally used optical disc reproducing device. The data recorded on the second recording layer 6 can be read following the reading of 15 and compatibility with a conventional optical disk can be provided.

The data recorded in the lead-in area 15 is read, and the first or second recording layer 4 or 6 is selected based on the data, and the light is applied to the first or second recording layer 4 or 6. When the beam is focused and scanning is started, the light beam returning from the first or second recording layer 4 or 6 is detected by the photodetector 36 having the four-segment detector 41 in the same manner as described above. Is done. The detection signal detected by the photodetector 36 is supplied to an RF amplifier 48. The RF amplifier 48 extracts a reproduced RF signal, a tracking error signal TE, a focus error signal FE, and the like by arithmetic processing of the supplied detection signal.

The extracted reproduced RF signal is supplied to the demodulation circuit 53. The tracking error signal TE and the focus error signal FE are supplied to the servo circuit 50.

The servo circuit 50 receives the supplied focus error signal FE, push-up signal PP, a track jump command from the system controller 52 constituted by a microcomputer, an access command, Various servo drive signals are generated based on rotation speed detection information of the spindle motor 31 and the like, and the drive circuit 49 controls the actuator 37 and the feed mechanism 33 to perform focus and tracking control. Control 1 to constant linear velocity (CLV).

The demodulation circuit 53 binarizes the reproduced RF signal supplied from the RF amplifier 48, demodulates the signal by, for example, an EFM (eight to fourteen modulation) method, and supplies the demodulated signal to the error correction circuit 54. The error correction circuit 54 corrects the error by a CIRC (cross interleaved Read Solomon coding) method, and the error-corrected data is supplied to a 0/8 conversion circuit 55, and the D / A conversion circuit 55 And output to the outside.

In addition, the system controller 52 supplies a control signal according to the operation content when the operation unit 56 is operated, and supplies the control signal to a display unit 57 that displays various operation statuses. I do.

In the case where data recorded on the recording layer having low reflectance among the first and second recording layers 4 and 6 is reproduced, it is desirable to perform control to increase the gain of the reproduced RF signal. . INDUSTRIAL APPLICABILITY As described above, the optical recording medium according to the present invention attenuates the transmission amount of a light beam by a lead-in area in which at least data required for reading data is recorded. Even if there are multiple recording layers, the lead-in The data recorded in the recording area can be accurately read, and data such as audio information and video information recorded in each recording layer can be accurately read and reproduced.

Further, the optical disc according to the present invention includes a data recorded in a read area provided in at least an area which is not affected by other recording layers and in which data necessary for reading data is recorded. After reading the data overnight, the data of each recording layer is read, so that the desired recording layer can be reliably selected and the desired data can be read reliably.

Claims

The scope of the claims

1. a substrate having optical transparency;

A first recording layer provided on one surface of the substrate,

A second recording layer provided so as to be stacked with the first recording layer and having at least a lead-in area in which data required for reading data is recorded;

An intermediate layer provided between the first recording layer and the second recording layer,

An optical recording medium in which the first recording layer is provided from outside the lead-in area.

2. The optical recording medium according to claim 1, wherein said lead-in area records at least a part of data necessary for reading data recorded on said first recording layer.

3. The optical recording medium according to claim 1, wherein data related to the reflectance of the first recording layer is recorded in the lead-in area.

4. The optical recording medium according to claim 1, wherein a data indicating that the first recording layer is provided is recorded in the lead-in area.

5. The optical recording medium according to claim 1, wherein the reflectance of one of the first recording layer and the second recording layer is higher than the reflectance of the other recording layer.

6. A substrate having optical transparency;

A first recording layer provided on one surface of the substrate, A second recording layer provided so as to be stacked with the first recording layer and having at least a lead-in area in which data required for data readout at a time is recorded;

An optical recording medium in which at least a portion of the first recording layer facing the lead-in area has a mirror surface.

7. The optical recording medium according to claim 6, wherein said lead-in area is recorded with at least a part of data necessary for reading data recorded on said first recording layer.

8. The mirror according to claim 6, wherein the mirror portion of the first recording layer is disposed in the direction of the read start position of the data readout of the lead-in area provided in the second recording layer. Optical recording medium.

9. The optical recording medium according to claim 6, wherein data is recorded on the first recording layer following the mirror surface portion.

10. The optical recording medium according to claim 6, wherein data related to the reflectance of the first recording layer is recorded in the lead-in area.

11. The optical disk according to claim 6, wherein data indicating that the first recording layer is provided is recorded in the lead-in area.

12. The optical recording medium according to claim 6, wherein the reflectance of one of the first recording layer and the second recording layer is higher than the reflectance of the other recording layer. .

1 3. A substrate having optical transparency;

It has at least a first recording layer and a second recording layer, and the first recording layer Either a recording layer or a second recording layer is provided on one surface of the substrate, and the other recording layer is provided so as to be laminated with the one recording layer and an intermediate layer, and at least data is read. An optical recording medium provided with a lead-in area that records data required for

14. The optical recording medium according to claim 13, wherein the lead-in area records at least a part of data necessary for reading data recorded on the first recording layer.

15. The optical recording medium according to claim 13, wherein the lead-in area has recorded therein data on the reflectance of the first recording layer.

16. The optical recording medium according to claim 13, wherein data indicating that the first recording layer is provided is recorded in the lead-in area.

17. The optical recording medium according to claim 13, wherein the reflectance of the one recording layer is lower than the reflectance of the other recording layer.

18. A substrate having a light-transmitting property, and at least a first recording layer and a second recording layer, wherein one of the first recording layer and the second recording layer is one of the substrates And the other recording layer is provided so as to be laminated with the one recording layer and the intermediate layer interposed therebetween, and at least a lead-in in which data necessary for reading data is recorded at least. Reading the data of the read-in area of the second recording layer of the optical recording medium provided with the area,

A method for reading an optical recording medium from which data in the first recording layer is read out after reading data in the lead-in area.

19. A substrate having a light transmitting property, a first recording layer provided on one surface of the substrate, and a first recording layer provided so as to be laminated on the first recording layer. At least a second recording layer having a lead-in area in which data necessary for reading data is recorded, and a second recording layer provided between the first recording layer and the second recording layer. An intermediate layer, wherein the first recording layer is provided from the outside of the lead-in area, and reads the data of the lead-in area of the second recording layer of the optical recording medium, and reads the data of the lead-in area. An optical recording medium reading method for reading out the data of the first recording layer after reading.

20. A substrate having a light transmitting property, a first recording layer provided on one surface of the substrate, and provided so as to be stacked with the first recording layer, and at least necessary for reading data. A second recording layer having a lead-in area on which data to be recorded is recorded, and an intermediate layer provided between the first recording layer and the second recording layer. At least a part of the first recording layer facing the lead-in area is read out from the lead-in area of the second recording layer of the optical recording medium having at least a part thereof as a mirror surface,

An optical recording medium reading method for reading data of the first recording layer after reading data of the read area.

2 1. Substrate and

A first recording layer provided on one surface of the substrate,

A second recording layer provided to be stacked with the first recording layer;

An optical recording medium wherein the first recording layer and the second recording layer are provided so as to be deviated from each other in the layer direction.

22. The optical recording medium according to claim 21, wherein said second recording layer is laminated so as to be read out before said first recording layer.

23. The second recording layer, wherein the recording start position of the second recording layer is provided so as to protrude more in the layer direction than the recording start position of the first recording layer. 22. The optical recording medium according to paragraph 22.

24. The optical recording medium according to claim 23, wherein the other ends of the first recording layer and the second recording layer are aligned.

25. The second recording layer is provided with a read area and a data recording area in which at least data necessary for reading data is recorded, and the read-in area includes the data recording area. 22. The optical recording medium according to claim 21, wherein said optical recording medium is provided at a position where said optical recording medium is read out before said area.

26. The optical recording according to claim 21, wherein the lead-in area records at least a part of data necessary for reading data recorded in the first recording layer. Medium.

27. The optical recording medium according to claim 21, wherein the lead-in area has recorded therein data relating to the reflectance of the first recording layer.

28. The optical recording medium according to claim 21, wherein data indicating that the first recording layer is provided is recorded in the lead-in area.

29. The optical recording according to claim 21, wherein the reflectance of one of the first recording layer and the second recording layer is higher than the reflectance of the other recording layer. Medium.

30. Recording from an optical recording medium having a first recording layer having a lead-in area provided in a state of being laminated on a substrate in the lead-in area Read the data

Based on the data read from the lead-in area, it is determined whether or not a second recording layer exists between the recording layer and the substrate. Then, when it is determined, an optical recording medium reading method for reading the second recording layer based on the control data recorded in the red line area.